PELARGONIUM Geranium cultivation techniques

This plant, with its bright heads of white, pink, red or purple flowers is found in gardens, greenhouses, window boxes, balconies and window sills everywhere. The Geranium is one of our favourite summer bedding plants, but it is not really a Geranium at all – it is the Zonal Pelargonium.

Look at one of the leaves of a typical variety and you will find a horseshoe markingor’zone’-that is wherethenamecomes from. These Zonal Pelargoniums are classified into three groups with somewhat indistinct dividing lines. The most popular ones belong to the Bedding Geranium group which flourish outdoors as well as under glass – the leaves are usually (but not always) zoned. The second group, the Greenhouse Geraniums, have a similar range of flowers and leaf markings but are disappointing outdoors. The Fancyleaf Geraniums make up the final group – here the leaf marking and colouring is more decorative than the blooms, which are generally (but not always) insignificant.

One of the great attractions of Pelargoniums to the enthusiast is the vast range of varieties which are available, and each year new types appear. Indoors the Zonal Pelargonium can be madeto bloom at any time of the year provided that the temperature is at least 50°F and the light is bright enough. With care you can have specimens in bloom in the greenhouse for nine months or even longer each year.

The universally popular Zonal types have an aristocratic relation – the Regal or Show Pelargonium. These are the beauties of the Pelargonium world with their shrubby growth, saw-edged leaves and large, bi-coloured ruffled flowers. But they do have problems-they will only succeed in a warm and sheltered spot outdoors and are best grown as indoor plants. The old varieties have a short

Flowering period: of two or three months, but the modern hybrids can be made to flower all the year round as long as there is sufficient light and warmth.

Another relative is the Ivyleaf Pelargonium, bearing fleshy leaves on trailing stems. In Britain it is used for hanging baskets, tubs and clothing trellis work, but in many other countries it is widely used for ground cover.

You don’t need green fingers to succeed with Pelargoniums. They have few pests or diseases and even fewer fussy demands. All they need is plenty of light and a free-draining soil. Propagation is easy – striking late summer, cuttings is the traditional method but the introduction of the F1 hybrid seed-raised varieties means that you can now produce Zonal Geraniumsforyourgarden aseasily as French Marigolds and Snapdragons.

The old favourites like ‘Paul Crampel’ still dominate the gardens of Britain, but there are now many types from which you can choose. There are Dwarfs which reach only 8 in. There are Stellars, Irenes, Rosebuds, Deacons and soon…. Miniatures growing less than 5 in. and Standards towering to 6 ft or more. Yet the Pelargonium is never truly at home in Britain. It must be lifted from the garden before the first frosts and allowed to sleep indoors until the end of May. Only in particularly favoured spots such as the Isles of Scilly can it grow outdoors as a perennial, and in a wet summer it produces an abundance of leaves and a paucity of flowers.

In the dry and frost-free areas of southern Europe the Pelargonium comes into its full glory. Here the Ivyleaf varieties can be seen cascading from balconies as shrubby perennials and on the hillsides the Zonal Pelargonium has become naturalised in an environment which reminds it of its native South Africa.

PLANT TYPES

Flowers Vi-1 in. across.

While, pink, salmon, red, purple

Rounded leaves; nearly all varieties having a horseshoe marking or’zone’

Any well-drained garden soil will do-the ideal is a sandy loam. Dig in compost or well-rotted manure before planting. Geraniums do best in full sun, but will tolerate light shade.

PLANTING OUT

Little can go wrong at planting time. All you have to do is choose a day in late May or early June when the danger of frost is past. The soil should be moist and the pots containing the Geraniums should have been watered a few hours before planting is due to begin. Plant firmly-that’s all there is to it. Yet failures do occur and the plants seem to stand still instead of growing away. The usual cause is the lack of hardening-off-the plants should have been progressively acclimatised to the new environment and not moved from a warm greenhouse to the cold outdoors in a single day.

PROPAGATION

Geranium cuttings root very easily. Use the ends of green shoots, about 3-4 in. long, and insert in Seed and Cutting Compost. Do not use a rooting hormone and do not cover the cuttings-a small Rooting Bag is ideal for Geranium propagation. Take cuttings in July or August-they will root in 2-3 weeks after which they should be moved to 3 in. pots containing Potting Compost. During the winter months apply water sparingly and move to a cold frame in early April to harden off the plants for their late May move to the open garden. F, Hybrids can be raised from seed-sow under glass in January.

SUMMER CARE

Pinch out the growing tips occasionally to increase thebushinessof the plants. Geraniums can withstand dry conditions better than most plants-constant watering is an easy way to kill them. Leave them alone, but if the dry weather is prolonged then a thorough soaking will be necessary. Feed occasionally with a liquid fertilizer which contains more potash than nitrogen. Remove the dead flowers to prolong the flowering season.

WINTER CARE

Before the first frosts arrive carefully dig up the plantsandshakeoffthesoil around the roots. Pot them up singly in Seed and Cutting Compost, using pots which are no largerthan necessary to house the roots. Reduce the height of the stems by about ahalfandcutoff all yellowing leavesand dead flower-heads. Put the pots in an unheated spare room or in a cold greenhouse. Do not feed them and water only when it is essential in order tostop the leaves from flagging. In spring move to a well-lit spot and increase the amount of water.

PESTS & DISEASES

The two main pests of Geraniums attack the plants when they are growing under glass. Aphids and whitefly can seriously weaken growth-spray with Bio Flydown. Grey mould is another indoor nuisance-avoid stuffy condi-tions and spray with a systemic fungicide. Black root rot and foot rot are caused by using non-sterile compost, overwatering or damp air around the plants-there is no cure.

CHELATE An organic chemical which can supply nutrients to plants in a soil which would normally lock up the plant-feeding element or elements in question.

CHIMAERA A mutation which produces two kinds of tissue – e.g one or more ‘wild’ coloured petals in a Chrysanthemum.

CHLOROPHYLL The green pigment found in leaves which is capable of using light-energy to transform carbon dioxide and water into carbohydrates by the process known as photosynthesis.

CHLOROSIS An abnormal yellowing or blanching of the leaves due to lack of chlorophyll.

CLOCHE A temporary structure of glass or plastic sheets used to protect and hasten the growth of plants in the open.

CLONE A group of identical plants produced by vegetative reproduction from a single parent plant.

COMPOSITAE The Daisy Family, in which each flower bears ‘petals’ which are really florets.

COMPOST Two meanings – either decomposed vegetable or animal matter for incorporation in the soil or a potting/cutting/seed sowing mixture made from peat (’soilless compost’) or sterilized soil (’loam compost’) plus other materials such as sand, chalk and fertilizers.

CROWN The bottom part of a herbaceous plant from which the roots grow downwards and the shoots arise.

CRUCIFERAE The Cabbage or Wallflower Family, in which the flower bears four petals in the shape of a cross.

CULTIVAR Short for ‘cultivated variety’ – it is a variety which originated in cultivation and not in the wild.

CYME A flat-topped or domed inflorescence in which the flowers at the centre open first.

D

DEAD-HEADING The removal of faded flowers.

DECIDUOUS A plant which loses its leaves at the end of the growing season.

DECUMBENT A prostrate stem with an ascending tip.

DENTATE Toothed margin.

DIBBER A blunt-ended wooden stick used to make holes in the soil for transplants.

DIGITATE LEAF A leaf composed of finger-like radiating leaflets.

DIOECIOUS A plant which bears either male or female flowers. Compare monoecious.

DISC (DISK) The flat central part of a compound flower. It is made up of short, tubular florets.

DORMANT PERIOD The time when a plant has naturally stopped growing due to low temperatures and short day length.

DOUBLE A flower with many more than the normal number of petals. When the whole of the bloom appears to be composed of petals it is called ‘fully double’-a ‘semi-double’ flower is the half-way point between a single bloom and a fully double one.

DRAWN Term applied to pale and lanky seedlings which Rave been sown too thickly or grown in shady conditions.

EVERGREEN A plant which retains its leaves in a living state during the winter.

EVERLASTING Flowers with papery petals which retain some or all of their colour when dried for winter decoration.

EYE Two meanings – a dormant growth bud or the centre of a single or semi-double bloom where the colour of this area is distinctly different from the rest of the flower.

F

FAMILY A group of related genera.

FEATHERED A petal on which there are feather-like markings on a ground colour which is distinctly different.

FERTILIZATION The application of pollen to the stigma to induce the production of seed.

FIBROUS-ROOTED A root system which contains many thin roots rather than a single tap root.

FILAMENT The supporting column of the anther. It is the lower part of the stamen.

FIMBRIATE Frilly-edged.

FLORE PLENO Term applied to double flowers.

FLORET The individual flowers of a compound flower or dense flower-head.

FLOWER The reproductive organ of the plant.

FOLIAR FEED A fertilizer capable of being sprayed on and absorbed by the leaves.

FORCING The inducement of flowering before its natural time.

FRIABLE Term applied to crumbly soil.

FROST POCKET An area where cold air is trapped during winter and in which half hardy plants are in much greater danger.

FRUIT The seed together with the structure which bears or contains it.

FUNGUS A primitive form of plant life which is the most common cause of infectious disease – e.g mildews and rusts. Such diseases are controlled or prevented by means of fungicides.

G

GENUS (plural GENERA) A group of closely-related plants containing one or more species.

GERMINATION The emergence of the root and shoot from the seed.

GLABROUS Smooth, hairless.

GLAUCOUS Covered with a bloom.

GROUND COLOUR The main or background colour of a petal.

GROUND COVER An ornamental plant which requires little attention and is used to provide a low-growing and weed-proof carpet between other plants.

H

HALF HARDY A plant which will only grow outdoors in Britain when the temperature is above freezing point. The term is not precise – some half hardy plants can be left outdoors in winter in mild regions of the country.

HARDENING OFF The process of gradually acclimatising a plant raised under warm conditions to the environment it will have to withstand outdoors.